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CHEMICAL AND PHYSICAL PROPERTIES, ETC. 217
used in a foundry. He writes the author that he has found it to greatly counteract the tendency of sulphur to increase combined carbon and that he has, upon several occasions where high sulphur was giving trouble in making castings hard, by increasing the phosphorus from 0.50 to 0.75 made castings soft, that cou.ld not otherwise be machined. Of course, he could have attained the same end by increasing the silicon or reducing the sulphur, but conditions permitted Mr. Beckett to experiment with phosphorus in order to obtain knowledge as to its exact influence when the other metalloids were remaining fairly constant. His experience in this line is of much value, and it gives the author pleasure to record them here, as Mr. Beckett is known to be a good manager. Mr. Beckett's experience in regulating mixtures by phosphorus also affirms that generally each tenth of one per cent, increase of phosphorus will give about the same results, physically, that an increase of one-quarter of one per cent, silicon will give, if the phosphorus is unchanged, until the total quantity of phosphorus reaches the limit of safety, viz., i.oo per cent., and that mixtures in which the fluidity is increased in this way within such limits will be found to produce castings freer from blow-holes and shrink spots than if silicon were entirely depended upon for giving fluidity. (See Chap. XXXI.) Chromium, as shown by Thomas Turner,* is not uncommonly present in small quantities in ordinary iron ores. It has been found as high as . 12 in samples of pig iron, by J. E. Stead, f It has increased the power of iron to absorb carbon up to 12 per cent.
•^Metallurgy of Iron, page 205.
flron and Steel Institute Journal, 1893, Vol. i, p. 168.ion of manga j: which was added being found in the form of oxide in the so-The philosophical explanation of this extraordinary effect i my opinion, to be found in the fact that the f erro-manganesu .»R. C. Hindiey, M. Hoskins, Harvard College, Havemeyer University, Henry Hiels Chemical Co., Isabella Furnace, Iron Gate Furnace, Iroquois Iron Co., Illinois Steel Co., Jefferson Iron Co., Kittan-ning Iron & Steel Co., C. A. Kelly Plow Co., Lebanon Furnace, Longdale Iron Co., Lackawanna Iron & Steel Co., Logan Iron........................ 16,720 " t-